Question: On Saturday, Michael's parents gave birth to twins and named them William and Daniel. When they were first born, William weighed 6.67 pounds, and Daniel weighed 8.21 pounds. How much did the babies weigh in total?
Answer: To find the weights of the 2 babies, we need to add their weights together. William's weight + Daniel's weight = total weight. ${6}$ ${6}$ ${7}$ ${8}$ ${2}$ ${1}$ ${+\vphantom{0}}$ ${8}$ ${8}$ ${4}$ ${1}$ Together, the babies weigh 14.88 pounds.